Airbus Helicopters is progressing with weekly flight tests of its DisruptiveLab demonstrator, as the airframer works to prove out technologies that it believes can deliver a 50% fuel-burn saving.
Unveiled at the Airbus Annual Summit in December 2022, the light-single-engined helicopter made its first flight in January this year.
Since then, the DisruptiveLab has made another four sorties, Tomasz Krysinski, head of research and technology, told journalists on 14 February during a briefing at the airframer’s Marignane site near Marseille. The most recent – conducted the same day – lasted 1h 5min.
DisruptiveLab combines a suite of technology developments which could be applied to future programmes to enhance performance.
Aerodynamic and weight improvements contribute to around 15% of the total, says Krysinski. Around 40 separate windtunnel campaigns were used to refine its shape, he notes.
He points to the “compact” main rotor hub, which is much more closely integrated with the fuselage thanks to a specially designed inter-blade damper. On its own, this innovation cuts drag by 40% over previous-generation helicopters, Krysinski says.
The 11.6m (38ft)-diameter main rotor blades are also of a new design, generating “much lower noise” than previously thanks to a thin tip profile “to reduce the interaction between the air and the blade”, and slower rotational tip speed. Besides noise, vibration levels have also been reduced, he adds.
While Airbus’s recent rotor blade innovations have led to designs like the hockey stick-shaped Blue Edge blades used on the H160 medium-twin, “for this one we applied different principles”, he says.
A redesigned tail boom and Fenestron ducted tail rotor have further contributed to the performance gains, Krysinski adds.
The overall diameter of the Fenestron has also been reduced. While that sees blade lengths reduced, a smaller, simplified hub means “the area of the blade that works is greater”, ensuring anti-torque performance is maintained. Part counts for the Fenestron have also been halved, cutting weight.
In addition, the “three-point” skid landing gear is “very well integrated” into the fuselage to reduce drag.
Further weight saving is achieved through an aluminium and composite fuselage, with the metallic components supplied by Airbus Atlantic – the group’s French aerostructures business – and composite parts from French firm Rexiaa.
But the largest chunk of the potential fuel-burn savings will come through powertrain improvements.
Safran Helicopter Engines has supplied the thermal engine for the DisruptiveLab, but Krysinski declines to disclose the engine model or if it is a clean-sheet design. However, he describes it as “a bit of a revolution”.
Crucially the powerplant is already provisioned for the programme’s next step: Airbus sees hybridisation of the engine contributing a further 10% fuel-burn saving.
At present, the electric motor and battery system are not installed on the DisruptiveLab as the airframer determines which suppliers to use for the programme. But Krysinski sees flights of the hybrid version within around 12 months.
“The electric motor is not there yet but it is designed to fit in a very clever way” that reduces the number of interfaces and cuts weight.
Krysinski says the electric motor will provide 250kW of power, enabling optimisation of the turbine during certain flight phases. The system will also be “reversible”, allowing in-flight recharging of the batteries.
Beyond fuel saving, he sees a safety boost from the hybridisation, with a helicopter able to fly for around 3min on battery power alone. Performance at altitude is also enhanced.
Overall lower fuel burn also “opens the door” to the use of 100% sustainable aviation fuel, and in future hydrogen, by offsetting their higher costs.